Heretofore the streamlining of the area between the cab top of the tractor vehicle and the upper front face of the trailer vehicle have been streamlined to reduce the resistance to travel.
I have now devised a construction wherein the end walls between the cab top and the upper front wall of the trailer vehicle can be pressure actuated to counter balance in part the effect of cross winds.
A further important feature of this invention is to provide cooling air to the refrigeration units, and to the provision of cooling air to keep the brakes from over heating and becoming ineffective to slow down and stop the vehicle.